Apparatus for simultaneous application of samples to thin layer chromatography plates

ABSTRACT

A thin layer chromatography apparatus with universal V-groove seats to support syringes and a movable arm with a resilient pad lowered and locked against the top of the syringes. An adjustable needle positioning means operates to align the tips of all the needles, and then is rotated to press down on the needles to selectively lower the tips relative to the plate. A variable drive member reciprocates a pusher member for the syringes, said drive member traveling along a rotatable screw which is reversible following contact of limit switches during travel of the drive member. A controlled heating element and air jets may be used to hasten rate of solvent evaporation during application of liquid samples to thereby assist reproductibility of sample application.

ilited States Patent [1 1 Cmins et al.

Evanston, Ill. by Blanche Perry, legal representative AnalyticalInstrument Specialties, Libertyville, Ill.

Filed: Sept. 24, 1971 Appl. No.: 183,365

Assignee:

US. Cl 210/198 C Int. Cl B0111 15/08 Field of Search 210/31 C, 198 CReferences Cited UNITED STATES PATENTS lO/l969 Blonneel 2l0/198 C l/l972Roddet 210/198 C June 12, 1973 3,667,917 6/1972 Brandt 210/198 C PrimaryExaminer-John Adee Attorney--Dominik, Kenchtel & Godula 57 ABSTRACT Athin layer chromatography apparatus with universal V-groove seats tosupport syringes and a movable arm with a resilient pad lowered andlocked against the top of the syringes. An adjustable needle positioningmeans operates to align the tips of all the needles, and then is rotatedto press down on the needles to selectively lower the tips relative tothe plate. A variable drive member reciprocates a pusher member for thesyringes, said drive member traveling along a rotatable screw which isreversible following contact of limit switches during travel of thedrive member. A controlled heating element and air jets may be used tohasten rate of solvent evaporation during application of liquid samplesto thereby assist reproductibility of sample application.

19 Claims, 8 Drawing Figures PAIENIED- 3 3; 738.493

sum 1 (IF 3 Fig. 1 66 A 7' TOPNE VS PAIENIEU Jim! 2 I975 3, 738 493SHEEI 2 UP 3 Fig. 5 g- 6 INVENTORS Laurence M. Cummms y Janet E. Perry ATTOPNEVS APPARATUS FOR SIMULTANEOUS APPLICATION OF SAMPLES TO THIN LAYERCHROMATOGRAPHY PLATES This invention relates to an apparatus fordelivering small volumes from one or more syringes onto thin layerchromatography (TLC) plates at slow delivery rates so that large volumesor samples can be deposited in small spots.

Both paper chromatography and TLC techniques are characterized bydeposit of a sample onto a surface and then identifying the compound orcompounds in the spotted sample by its pattern of migration on thesurface of a chromatographic development. There is a recognizedrelationship between physical and chemical properties and rate ofmigration. Both procedures often use a plurality of syringes to deposita number of adjoining samples onto the surface. This increases theefficiency in that a greater number of analyses may be conducted andcompared on one paper strip or TLC plate. The art has come to recognizethat one important problem is the spreading and overlapping of adjoiningspots on the surface. This understandably interferes or nullifies theresults.

The desired goal is to deposit as large a sample as possible on as smalla spot as possible. In this way, a large amount of compound or solutewill be deposited on a very small area. The paper chromatography art hasdeveloped the approach of depositing the sample in very small volumesand at a very slow rate so that the volatile solvent carrier evaporatesas the drop is formed so that more solute and less solvent is depositedas the spot on the surface. Micropipettes have been used to serve thispurpose as well as microsyringes in which the plunger is slowly actuatedmanually at a slow rate.

It is one important object of the present invention to provide a TLCapparatus in which a plurality of syringes are disposed for depositingminute volumes of sample onto TLC plates in an improved manner.

Another important object of the present invention is to provide a TLCapparatus of an improved design in which a gang of syringes areimmobilized in a means which can accommodate a variety of syringe barreldiameters without requiring special fittings, adjustments, or the like.

Still another important object of the present invention is to provide aTLC apparatus of improved design wherein aligned needles in a gang ofsyringes are adjustably repositioned relative to a TLC plate by meanswhich are quickly and reliably actuated to move the gang of needles toany one of a number of positions which may be selected.

Still yet another important object of the present invention is toprovide a TLC apparatus of improved design which allows quick andreliable infinite adjustment of a gang of syringe needles so that thetips of all the needles are identically repositioned relative to a TLCplate.

Yet another important object of the present invention is to provide aTLC apparatus of improved design in which a pusher member for a gang ofsyringes executes forward and reverse travel under control of a drivemember which reciprocates along a driving means with control limits tostop and reverse the travel therealong.

Still yet another important object is an improved TLC apparatus havingcontrolled heating means for inducing rapid solvent evaporation whileapplying the sample, as well as optionally operated airjet means usefulfor hastening solvent evaporation in the presence of heat labilecompounds.

Such objects are now attained, together with still other objects whichwill become evident from time to time by considering the invention inthe following disclosure, which includes drawings wherein:

FIG. 1 is a top plan view of the improved apparatus of the invention;

FIG. 2 is a side elevational view of the apparatus of FIG. 1;

FIG. 3 is a sectional view along line 33 of FIG. 1;

FIG. 4 is a side sectional view on an enlarged scale, of the apparatus,with portions removed;

FIG. 5 is a portional section view along line 5-5 of FIG. 4;

FIG. 6 is a portional section view along line 66 of FIG. 4;

FIG. 7 is a portional side view partly in section, showing the needleadjustment means in needle positioning attitude; and

FIG. 8 is a portional top plan view, partly in section, and on the samescale as FIGS. 5-7, showing manual means for infinitely adjusting theneedle repositioner.

The use of the same numerals in the various views of the drawings willindicate a reference to like parts, structures or elements, as the casemay be.

Referring now to the drawings, the apparatus illustrated includes agenerally box-like housing 10 having opposed sidewalls l2, opposed endwalls 14, a top wall 16, and a bottom wall or floor 17. On the top wallof the housing is positioned a TLC glass plate 18 which inner edge iscorrectly positioned by a transverse stop element 19. One side of theplate is contacted by a spring urged ram 20 of a pusher member 21mounted to top wall 16, the spring mechanism not being shown. A pair ofopposite position pins 22 fix the position of the plate against thepusher 21. An electrical heater element 23 is shown under the glass sothat it is located below the sample spotting site. The heating elementspans the spotting sites, and its temperature is adjusted by means suchas variable resistance to hasten evaporation of solvent in the sample.

The TLC glass plate is conventionally prepared, and mono-dimensionalhigh voltage thin-layer electrophoresis, that is, for TLC procedures.After the TLC plate is spotted according to the teaching of the presentinvention, it is conventionally processed to quantify the depositedspots for identifying the compounds deposited at such spots.

A syringe grouping or gang shown generally as 24 extends transverselyalong the top of the housing. Each syringe is identified by the usualsyringe barrel 25, syringe plunger 26 with head 27, and needle 28.

A pusher element or bar 39 also extends transversely along the top ofthe housing for contacting heads 27 of the syringes.

A hold down means shown generally as 34 also extends transversely alongthe top of the housing. The hold down means includes a spanning arm 35which is joined by a pivot 36 to pivot plate 37 which is opposed bylocking plate 38. The opposite end of the pivotable spanning arm 35 hasan interlock assembly, shown with a translatable pin 39 in an oversizedlocking aperture 40. A detent 41 has a tapered opening 42 engageable bytapered face 43 of pin 39. The detent is urged outwardly into lockingengagement with catch 44 fixed to locking plate 38. Pin 39 may bepressed downwardly to move detent 41 out of locking engagement, said pin39 thereby being translatable in oversized aperture 40 towards pivotplate 37.

Bottom three point supports for the syringe are positioned on the topwall 16 of the housing. The supports are shown as three transversewalls, lower syringe support 45, upper syringe support 46, andintermediate syringe support 47. The top edge of each support wall isprovided with a plurality of universal syringe V-seats 48, the threewalls providing three aligned V-seats for each syringe. Such V -seatsallow syringe barrels of varying diameters to be seated therein, as willbe readily understood.

The hold down means for the syringes is also shown as including anelongated resilient pad 54 mounted to the arm 35. It will be seen thatwhen the pivotable arm is fully lowered so that the interlock assemblyis actuated, the resilient pad and arm will accommodate themselves tothe particular syringe barrel diameter seated in aligned V-seats in thetransverse wall supports. This will assure the immobility of the gang ofsyringes during operation of the apparatus.

The selective adjustment or needle positioning means, includes anelongated bar 62 with opposite end right angle walls 63. Such bartherefore assumes the profile of an angle element. The end walls 63 arepivoted to opposite upright walls 37, 38 at pivots 64. The bar orelement 62 has a flat surface to position the tips of the needles inalignment. An air tube 65 extends to the opposite end walls 63, and suchtube is connected to a source of compressed air (not shown) through line66. The end walls 63 have journal openings for the air tube so thatselective positioning means may be rotated around the tube. A pluralityof air jets 67 are on the underside of the tube, aligned along thelength of the tube and generally coincidental with the ends of theneedles. Controls, not shown, actuate passage of air through the tubeand out the openings as pressurized jets to hasten evaporation ofsolvent when the compounds are heat labile.

The opposite end wall 63 is shown pivoted to an infinite adjustmentmeans, shown generally as 68. Such means include a flanged head pin 69which has a knurled stub 70 which is non-rotatably fitted in wall bore71. The shank 72 of the pin is rotatable within bearing 73. The infiniteadjustment means is actuated by manually rotating knob 74. Such knob hasan upper enlarged recess 75 which communicates with narrow passage 76. Apair of opposed belleville springs collectively shown as 77 are disposedwithin the upper large recess 75. Such springs are fixed to shank 72 ofthe pin so that the combination of the belleville springs urges onespring against the upright wall and the outer spring against the bottomof upper recess 75. A reduced diameter portion 78 is provided in theshank of the pin, and said portion is aligned with threaded set screwpassageway 79 in the knob. A set screw 80 fixes the pin 69 upon movinginto a part of narrow passage 76 provided by reduced diameter portion78.

The elongated angle is rotated substantially 180 from the positiongenerally shown in FIG. 4 to the position generally shown in FIG. 7.This rotation is effected by manually rotating knob 74 which can bestopped at any one of an infinite number of positions in theory. Theopposed belleville springs provide sufficient frictional contact betweenthe knob and the housing part to stop the element in any rotatedposition. In this way, an edge of the elongated element as shown in FIG.7, contacts the top of the needles and moves them downward until the tipof the needles are selectively positioned relative to the TLC plate 18.

The apparatus is provided with a control board 84 provided with anon-off master switch S, and a test start switch T to start the motor. Anadjustable heat control H has graduations to control the temperature ofelement 23, such temperature being read on pyrometer P. A calibratedcontrol C adjusts the rotational speed of screw 89 through fixedgradations of from 1 to 10. Such conventional controls are used tooperate electric motor 85 which is joined to a gear train box 86 havinga desired gear reduction to rotate stub shaft shown threadably engagedin threaded bore 88 of transmission coupling 87. An end of a rotatablescrew shaft 89 is also shown threadably engaged in the bore of thecoupling transmission.

A drive means shown generally as 90 is reciprocally driven along therotatable screw shaft 89 which is turned at desired rotational speeds.The drive means includes a body member 91 having a cutout 92 which opensat the back wall 93 and the top wall 94 of the body member. A drivingarm 95 is pivoted within the cutout at 95a, and such arm extends out oftrack or groove 96 in the top wall 16 of the housing. A belleville typespring 97 normally urges the driving arm 95 into normal relationshipwith the plane of the top wall 16. Spring 98 within the cutout 92 alsourges the driving arm into normal relationship with the plane of the topwall 16.

A pin 99 is fixed to a lower part of the driving arm 95, and the spring98 also urges this pin out of contact with microswitch 100. The end ofthe pin 99 is shown with a flange 101 to prevent such pin from slippinginto cutout 92 under urgings of the spring 98. When the driving arm 95reaches a limit of travel as defined either by closed end 102 of trackslot 96, or the fully inserted positions of the plungers 27 in thesyringes, such driving arm will rotate or pivot counterclockwiserelative to the view of FIG. 4. Such pivotable movement will urge pin 99out of the body member 91, and into contact with microswitch 100. Thismicroswitch will then reverse the rotation of screw 89 and therebyreverse the travel of the drive means along said screw towards the backof the housing. Travel of the drive means along the screw towards therear of the housing will be stopped when back wall 93 of the body memberengages contact 106 of a microswitch mounted to backwall 14 of thehousing. The actuated microswitch will turn off motor 85, and terminaterotation of screw 89. It will be evident that driving arm 95 may be alsomanually pivoted to reverse the path of travel of the drive means,thereby affording the user of the apparatus added versatility in theoperation thereof.

The bottom wall 108 of the drive member 91 has a threaded semicirculargroove 109 which is engaged by the threads of screw 89. The body memberis held to the screw by U-shaped clip 110 which is fixed to the oppositesidewalls 111 of the drive member by fasteners 112. The clip has foreand aft bearing pads 114 which slidingly engage the bottom of the screw89. The clip allows the half nut groove 109 to retain effectiveengagement with the screw 89 during reciprocal travel of the drivemember and during pivotable movement of the driving arm 95.

The claims of the invention are now presented.

We claim:

1. An apparatus for delivering small volumes from a syringe onto a thinlayer chromatography plate, includmg a housing,

a thin layer chromatography plate on said housing,

a syringe support on said housing,

means to immovably hold said syringe on said support,

a pusher element translatable along said housing to push a plunger ofsaid syringe,

means in said housing to move said pusher element at selectedvelocities, and

adjustable means to releasably engage the top of said needle and urgesame downwardly so that the needle tip is desirably repositionedrelative to said thin layer chromatography plate, said needle returningto its original position upon disengagement of said adjustable means.

2. An apparatus which includes the features of claim 1 above, whereinsaid adjustable means further includes a needle positioning means tointercept the tip of said needle to desirably position the end of saidneedle along the length of said thin layer chromtography plate.

3. An apparatus which includes the features of claim 2 above, whereinsaid adjustable means is an elongated, rotatable element which spans thehousing and is pivoted at its opposite ends to housing parts, andwherein an edge of said elongated element contacts the top of the needlewhen said element is rotated about 180, continued rotation urging saidneedle downwardly to selectively position the needle tip relative to thethin layer chromatography plate.

4. An apparatus which includes the features of claim 3 above, whichfurther includes manually rotatable means connected to said elongatedelement, and resilient means intermediate said knob and elongatedelement which hold said rotatable element to the position to which it isrotated by said manual means.

5. An apparatus which includes the features of claim 4 above, whereinsaid resilient means are oppositely urged against said manual means andagainst a housing part, and wherein said oppositely urged resilientmeans allow infinite adjustment in rotating said elongated element.

6. An apparatus which includes the features of claim 5 above, wherein agroup'of syringes are aligned on said syringe support, and wherein saidholding means span said housing and simultaneously hold all of saidaligned syringes on said support.

7. An apparatus which includes the features of claim 6 above, whereinsaid elongated element has a flat surface element which intercepts theneedles of all the syringes to align same along the length of the thinlayer chromatography plate, and wherein an edge of said flat surfaceelement engages the tops of the aligned needles upon rotation.

8. An apparatus which includes the features of claim 1 above, whereinsaid syringe support extends transversely on said housing, said supportincluding a plurality of substantially parallel walls, and alignedV-groove seats at the top edges of each wall to accommodate a syringbarrel of varying diameter, and wherein the means to immovably hold thesyringe includes an elongated hold down member movable to engage aplurality of syringe barrels, each of which is seated in said alignedV-grooved seats, and means to interlock said elongated member in loweredposition against such syringe barrels.

9. An apparatus which includes the features of claim 8 above, whereinsaid hold down member is pivoted at one of its ends to a housing part,the opposite end having means to form an interlock with another housingpart when said hold down member is lowered to engaging position, and anelongated resilient element mounted on said hold down member forcontacting the syringe barrels.

10. An apparatus which includes the features of claim 1 above, whereinsaid pusher element moves along a track extending along the top of thehousing, and wherein said pusher element is connected to a drive memberwithin the housing, said drive member adapted to be driven along arotatable screw, and said screw being rotated by electric motor meansjoined to control means which may be operated to attain desiredrotational speeds for advancing said drive member at desired velocities.

11. An apparatus which includes the features of claim 10 above whereinsaid drive member carries a pivotable drive arm, one end whereof extendsout of said track against said pusher element, said drive arm beingpivoted upon encountering predetermined resistance of the pusher elementwhich occurs upon discharge of said syringes, and said pivoted armactuating reversing means for said screw to induce travel of the drivemeans in a direction away from the syringes.

12. An apparatus which includes the features of claim 11 above, whichfurther includes an opposed stop means to intercept said drive member inits rearward travel along said rotatable screw to stop the rotation ofthe screw and the rearward direction of said drive means.

13. An apparatus which includes the features of claim 11 above, whereinsaid reversing and stop means are microswitches, the reversingmicroswitch being carried by said drive means, and the stop microswitchbeing mounted on a rear wall of the housing in the path of travel ofsaid drive means.

14. An apparatus which includes the features of claim 1 above, whereinsaid pusher element extends transversely along said housing, a pluralityof syringes ganged together in aligned position so that each of theplunger heads contact said pusher element in fully closed position, saidneedle positioning means having a transverse element with a flatsurface, and the needles of said ganged syringes aligned in abuttingrelationship with said transverse element.

15. An apparatus which includes the features of claim 14 above, whereina track extends along the top of said housing, and a drive arm contactssaid pusher element, said drive arm being pivotally linked to a drivemember within said housing which is reciprocally driven along arotatable screw at selected speeds, said drive member carrying reversingmeans actuated by said drive arm when pivoted by resistance from saidpusher member.

16. An apparatus which includes the features of claim 5 above, whereinsaid syringe support includes parallel walls extending transverselyalong said housing, the top edges of each of said walls having alignedV-groove seats to accommodate syringe barrels of varying diameters, andwherein said hold down member has a pivotally movable arm having anelongated, resilient pad mounted to the underside, said pad contactingthe top of the syringe barrels when lowered, and the non-pivoted end ofsaid arm having means to form an interlock with the housing part whenfully lowered to immobilize said ganged syringes.

17. An apparatus which includes the features of claim 16 above, whereinthe transverse element of the needle positioning means releasablyengages the top of said needles, said transverse element being manuallyrotatable about 180 to engage the top of said needles, and saidtransverse element being locked in a selected ited samples to hastensolvent evaporation.

1. An apparatus for delivering small volumes from a syringe onto a thinlayer chromatography plate, including a housing, a thin layerchromatography plate on said housing, a syringe support on said housing,means to immovably hold said syringe on said support, a pusher elementtranslatable along said housing to push a plunger of said syringe, meansin said housing to move said pusher element at selected velocities, andadjustable means to releasably engage the top of said needle and urgesame downwardly so that the needle tip is desirably repositionedrelative to said thin layer chromatography plate, said needle returningto its original position upon disengagement of said adjustable means. 2.An apparatus which includes the features of claim 1 above, wherein saidadjustable means further includes a needle positioning means tointercept the tip of said needle to desirably position the end of saidneedle along the length of said thin layer chromtography plate.
 3. Anapparatus which includes the features of claim 2 above, wherein saidadjustable means is an elongated, rotatable element which spans thehousing and is pivoted at its opposite ends to housing parts, andwherein an edge of said elongated element contacts the top of the needlewhen said element is rotated about 180*, continued rotation urging saidneedle downwardly to selectively position the needle tip relative to thethin layer chromatography plate.
 4. An apparatus which includes thefeatures of claim 3 above, which further includes manually rotatablemeans connected to said elongated element, and resilient meansintermediate said knob and elongated element which hold said rotatableelement to the position to which it is rotated by said manual means. 5.An apparatus which includes the features of claim 4 above, wherein saidresilient means are oppositely urged against said manual means andagainst a housing part, and wherein said oppositely urged resilientmeans allow infinite adjustment in rotating said elongated element. 6.An apparatus which includes the features of claim 5 above, wherein agroup of syringes are aligned on said syringe support, and wherein saidholding means span said housing and simultaneously hold all of saidaligned syringes on said support.
 7. An apparatus which includes thefeatures of claim 6 above, wherein said elongated element has a flatsurface element which intercepts the needles of all the syringes toalign same along the length of the thin layer chromatography plate, andwherein an edge of said flat surface element engages the tops of thealigned needles upon rotation.
 8. An apparatus which includes thefeatures of claim 1 above, wherein said syringe support extendstransversely on said housing, said support including a plurality ofsubstantially parallel walls, and aligned V-groove seats at the topedges of each wall to accommodate a syring barrel of varying diameter,and wherein the means to immovably hold the syringe includes anelongated hold down member movable to engage a plurality of syringebarrels, each of which is seated in said aligned V-grooved seats, andmeans to interlock said elongated member in lowered position againstsuch syringe barrels.
 9. An apparatus which includes the features ofclaim 8 above, wherein said hold down member is pivoted at one of itsends to a housing part, the opposite end having means to form aninterlock with another housing part when said hold down member islowered to engaging position, and an elongated resilient element mountedon said hold down member for contacting the syringe barrels.
 10. Anapparatus which includes the features of claim 1 above, wherein saidpusher element moves along a track extending along the top of thehousing, and wherein said pusher element is connected to a drive memberwithin the housing, said drive member adapted to be driven along arotatable screw, and said screw being rotated by electric motor meansjoined to control means which may be operated to attain desiredrotational speeds for advancing said drive member at desired velocities.11. An apparatus which includes the features of claim 10 above whereinsaid drive member carries a pivotable drive arm, one end whereof extendsout of said track against said pusher element, said drive arm beingpivoted upon encountering predetermined resistance of the pusher elementwhich occurs upon discharge of said syringes, and said pivoted armactuating reversing means for said screw to induce travel of the drivemeans in a direction away from the syringes.
 12. An apparatus whichincludes the features of claim 11 above, which further includes anopposed stop means to intercept said drive member in its rearward travelalong said rotatable screw to stop the rotation of the screw and therearward direction of said drive means.
 13. An apparatus which includesthe features of claim 11 above, wherein said reversing and stop meansare microswitches, the reversing microswitch being caRried by said drivemeans, and the stop microswitch being mounted on a rear wall of thehousing in the path of travel of said drive means.
 14. An apparatuswhich includes the features of claim 1 above, wherein said pusherelement extends transversely along said housing, a plurality of syringesganged together in aligned position so that each of the plunger headscontact said pusher element in fully closed position, said needlepositioning means having a transverse element with a flat surface, andthe needles of said ganged syringes aligned in abutting relationshipwith said transverse element.
 15. An apparatus which includes thefeatures of claim 14 above, wherein a track extends along the top ofsaid housing, and a drive arm contacts said pusher element, said drivearm being pivotally linked to a drive member within said housing whichis reciprocally driven along a rotatable screw at selected speeds, saiddrive member carrying reversing means actuated by said drive arm whenpivoted by resistance from said pusher member.
 16. An apparatus whichincludes the features of claim 5 above, wherein said syringe supportincludes parallel walls extending transversely along said housing, thetop edges of each of said walls having aligned V-groove seats toaccommodate syringe barrels of varying diameters, and wherein said holddown member has a pivotally movable arm having an elongated, resilientpad mounted to the underside, said pad contacting the top of the syringebarrels when lowered, and the non-pivoted end of said arm having meansto form an interlock with the housing part when fully lowered toimmobilize said ganged syringes.
 17. An apparatus which includes thefeatures of claim 16 above, wherein the transverse element of the needlepositioning means releasably engages the top of said needles, saidtransverse element being manually rotatable about 180* to engage the topof said needles, and said transverse element being locked in a selectedposition following engagement with the top of said needles to desirablylower the tips of the needles relative to said thin layer chromatographyplate.
 18. An apparatus which includes the features of claim 14 above,which further includes a transverse heating element extending below thealigned tips of said needles to hasten solvent evaporation.
 19. Anapparatus which includes the features of claim 14 above, which furtherincludes a transverse air tube carried by said transverse element, aplurality of air jets in said tube for directing air jets into thedeposited samples to hasten solvent evaporation.